SUMMARY/ABSTRACT Over 1.3 million people in the USA are infected with HIV and almost half suffer from HIV-associated neurocognitive disorders (HAND), despite having access to antiretroviral therapy (ART). Our recent findings show mitochondrial dysfunction may play a crucial role in the neurodegenerative process involved in HAND. The research goals of this K01 proposal are to determine how dysfunctional mitochondria contribute to the progression of HAND in the era of ART. The training goals are for the applicant to attain expertise in transcriptomics and mitochondrial bioenergetics research. Mitochondria power the body by performing the final steps of converting the food we eat into the molecular units of energy our cells can use. Maintaining a healthy pool of mitochondria requires generation of new mitochondria and recycling of old mitochondria. We've recently discovered that in brains of HAND decedents, there is blockage in both the generation of new mitochondria and recycling of damaged mitochondria. The mechanisms of neurodegeneration causing HAND are not completely understood, however our previous findings show that HIV proteins can alter the splitting and conjoining of mitochondria, and this results in mitochondrial enlargement and damage. New data suggest that in HAND brains, cells attempt generate new mitochondria, but the process is blocked prematurely. To extend these studies, we hypothesize that disruption in mitochondrial biogenesis and downstream effects on bioenergetics are key neurodegenerative mechanisms driving HAND. We will test this hypothesis in two Specific Aims: AIM 1: Investigate mitochondrial biogenesis-related gene expression networks in brains of HIV+ decedents who were on ART, and in a mouse model expressing HIV proteins in the brain. In Aim 1, mitochondrial biogenesis will be investigated using brain tissues from a cohort of HAND decedents, and from mice expressing HIV proteins in the brain. Mitochondrial biogenesis gene expression in brains will be determined by RNA sequencing (seq) and transcriptomic analyses. Findings will then be validated using biochemical and microscopy methods. We will further investigate the how HIV proteins or ART affect mitochondria in AIM 2: Determine the underlying mechanisms of disrupted mitochondrial biogenesis and bioenergetics in neurons exposed to gp120, Tat and/or ART, in vitro. For Aim 2, mitochondrial activity of neurons will be measured after knockdown and overexpression of mitochondrial biogenesis pathway proteins in human primary neuroglial cultures treated with HIV proteins or ART. Using these experiments, we will identify important interactions between HIV proteins or ART and mitochondrial biogenesis, and the effects on neuronal bioenergetic capacity. The information gathered from these studies may lead to novel therapeutic targets in ART-era HAND patients and novel mechanisms of dysfunctional mitochondrial biogenesis and bioenergetics that could be relevant to other neurodegenerative diseases.